| 31. |
- Rattfält, Linda, 1979-, et al.
(författare)
-
Robust heartbeat detector based on weighted correlation and multichannel input : Implementation on the ECG recorded with textile electrodes
- 2013
-
Ingår i: International Journal of E-Health and Medical Communications. - : IGI Global. - 1947-315X .- 1947-3168. ; 4:1, s. 61-71
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to develop and evaluate a robust heartbeat detector for noisy electrocardiograms (ECGs) recorded with textile electrodes. The authors suggest a method based on weighted correlation in a multi-channel ECG to obtain a heartbeat detector. Signals were acquired during rest and at movements which simulate every day activities. From each recording a segment corresponding to a heartbeat was extracted and correlated with the whole signal. From the correlation data, heartbeat candidates were derived and weighted based on their variance similarity with the heartbeat model and previous heartbeats. Finally, the outputs of each channel were added to create the global output. The output was compared to the Pan Tompkins heartbeat detector. Results are promising for recordings at rest (sensitivity = 0.97, positive predictive value (PPV) = 0.97). For static muscle tension in the torso the results were much higher than the reference method (sensitivity = 0.77, PPV = 0.85). Corresponding values for the reference method were sensitivity = 0.96 and PPV = 0.95 at rest and sensitivity = 0.52 and PPV = 0.75 during muscle tension.
|
|
| 32. |
|
|
| 33. |
|
|
| 34. |
- Romu, Thobias, et al.
(författare)
-
MANA - Multi scale adaptive normalized averaging
- 2011
-
Ingår i: 2011 IEEE International Symposium on Biomedical Imaging: From Nano to Macro. - : IEEE conference proceedings. - 9781424441280 ; , s. 361-364
-
Konferensbidrag (refereegranskat)abstract
- It is possible to correct intensity inhomogeneity in fat–water Magnetic Resonance Imaging (MRI) by estimating a bias field based on the observed intensities of voxels classified as the pure adipose tissue. The same procedure can also be used to quantify fat volume and its distribution which opens up for new medical applications. The bias field estimation method has to be robust since pure fat voxels are irregularly located and the density varies greatly within and between image volumes. This paper introduces Multi scale Adaptive Normalized Average (MANA) that solves this problem bybasing the estimate on a scale space of weighted averages. By usingthe local certainty of the data MANA preserves details where the local data certainty is high and provides realistic values in sparse areas.
|
|
| 35. |
|
|
| 36. |
- Sundvall, Erik, 1973-
(författare)
-
Scalability and Semantic Sustainability in Electronic Health Record Systems
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work is a small contribution to the greater goal of making software systems used in healthcare more useful and sustainable. To come closer to that goal, health record data will need to be more computable and easier to exchange between systems.Interoperability refers to getting systems to work together and semantics concerns the study of meanings. If Semantic interoperability is achieved then information entered in one information system is usable in other systems and reusable for many purposes. Scalability refers to the extent to which a system can gracefully grow by adding more resources. Sustainability refers more to how to best use available limited resources. Both aspects are important.The main focus and aim of the thesis is to increase knowledge about how to support scalability and semantic sustainability. It reports explorations of how to apply aspects of the above to Electronic Health Record (EHR) systems, associated infrastructure, data structures, terminology systems, user interfaces and their mutual boundaries.Using terminology systems is one way to improve computability and comparability of data. Modern complex ontologies and terminology systems can contain hundreds of thousands of concepts that can have many kinds of relationships to multiple other concepts. This makes visualization challenging. Many visualization approaches designed to show the local neighbourhood of a single concept node do not scale well to larger sets of nodes. The interactive TermViz approach described in this thesis, is designed to aid users to navigate and comprehend the context of several nodes simultaneously. Two applications are presented where TermViz aids management of the boundary between EHR data structures and the terminology system SNOMED CT.The amount of available time from people skilled in health informatics is limited. Adequate methods and tools are required to develop, maintain and reuse health-IT solutions in a sustainable way. Multiple levels of modelling including a fixed reference model and another layer of flexible reusable ‘archetypes’ for domain specific data structures, is an approach with that aim used in openEHR and the ISO 13606 standard. This approach, including learning, implementing and managing it, is explored from different angles in this thesis. An architecture applying Representational State Transfer (REST) to archetype-based EHR systems, in order to address scalability, is presented. Combined with archetyping this architecture also aims at enabling a sustainable way of continuously evolving multi-vendor EHR solutions. An experimental open source implementation of it, aimed for learning and prototyping, is also presented.Manually changing database structures used for storage every time new versions of archetypes and associated data structures are needed is likely not a sustainable activity. Thus storage systems that can handle change with minimal manual interventions are desirable. Initial explorations of performance and scalability in such systems are also reportedGraphical user interfaces focused on EHR navigation, time-perspectives and highlighting of EHR content are also presented – illustrating what can be done with computable health record data and the presented approaches.Desirable aspects of semantic sustainability have been discussed, including: sustainable use of limited resources (such as available time of skilled people), and reduction of unnecessary risks. A semantic sustainability perspective should be inspired and informed by research in complex systems theory, and should also include striving to be highly aware of when and where technical debt is being built up. Semantic sustainability is a shared responsibility.The combined results presented contribute to increasing knowledge about ways to support scalability and semantic sustainability in the context of electronic health record systems. Supporting tools, architectures and approaches are additional contributions.
|
|
| 37. |
- Thomas, Marianna S, et al.
(författare)
-
Test-retest reliability of automated whole body and compartmental muscle volume measurements on a wide bore 3T MR system
- 2014
-
Ingår i: European Radiology. - : Springer Berlin/Heidelberg. - 0938-7994 .- 1432-1084. ; 24:9, s. 2279-2291
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:To measure the test-retest reproducibility of an automated system for quantifying whole body and compartmental muscle volumes using wide bore 3 T MRI.MATERIALS AND METHODS:Thirty volunteers stratified by body mass index underwent whole body 3 T MRI, two-point Dixon sequences, on two separate occasions. Water-fat separation was performed, with automated segmentation of whole body, torso, upper and lower leg volumes, and manually segmented lower leg muscle volumes.RESULTS:Mean automated total body muscle volume was 19·32 L (SD9·1) and 19·28 L (SD9·12) for first and second acquisitions (Intraclass correlation coefficient (ICC) = 1·0, 95 % level of agreement -0·32-0·2 L). ICC for all automated test-retest muscle volumes were almost perfect (0·99-1·0) with 95 % levels of agreement 1.8-6.6 % of mean volume. Automated muscle volume measurements correlate closely with manual quantification (right lower leg: manual 1·68 L (2SD0·6) compared to automated 1·64 L (2SD 0·6), left lower leg: manual 1·69 L (2SD 0·64) compared to automated 1·63 L (SD0·61), correlation coefficients for automated and manual segmentation were 0·94-0·96).CONCLUSION:Fully automated whole body and compartmental muscle volume quantification can be achieved rapidly on a 3 T wide bore system with very low margins of error, excellent test-retest reliability and excellent correlation to manual segmentation in the lower leg.KEY POINTS:• Sarcopaenia is an important reversible complication of a number of diseases. • Manual quantification of muscle volume is time-consuming and expensive. • Muscles can be imaged using in and out of phase MRI. • Automated atlas-based segmentation can identify muscle groups. • Automated muscle volume segmentation is reproducible and can replace manual measurements.
|
|
| 38. |
|
|
| 39. |
|
|
| 40. |
- Åstrand, Olov, et al.
(författare)
-
Weight gain by hyperalimentation elevates C-reactive protein levels but does not affect circulating levels of adiponectin or resistin in healthy subjects
- 2010
-
Ingår i: European Journal of Endocrinology. - Bristol : BioScientifica. - 0804-4643 .- 1479-683X. ; 163:6, s. 879-885
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Increase of resistin and/or reduction of adiponectin have beenimplicated in the development of insulin resistance followingweight gain. We aimed to study this prospectively in humans.Design: Prospective and interventional with parallel control group.Methods: Twelve healthy men and six healthy women (age 26±6.6years) and an age-matched control group were recruited. Subjectsin the intervention group aimed for a bodyweight increase of5–15% by doubling the baseline caloric intake by eatingat least two fast food-based meals a day in combination withadoption of a sedentary lifestyle for 4 weeks.Results: Bodyweight increased from 67.6±9.1 to 74.0±11kg, P<0.001, by the intervention. Insulin levels increased(before: 27.4±12 pmol/l, after: 53.0±22 pmol/l,P=0.004), while plasma levels of adiponectin (before: 5038±3736ng/ml, after: 6739±7949 ng/ml, P=0.18) and resistin (before:21.8±19 ng/ml, after: 14.4±6.8 ng/ml, P=0.074)remained unchanged by the weight gain and were similar as incontrols. On the other hand, leptin levels increased about threefoldfollowing the intervention (before: 5.7±7.4, after: 16±20ng/ml, P=0.008), and also the inflammatory marker C-reactiveprotein (CRP) increased from 0.34±0.44 to 0.71±0.87mg/l, P=0.03, when two outliers >10 mg/l were disregarded.Conclusions: Hyperalimentation reduces insulin sensitivity when weight gainof 9% was combined with reduction of exercise. However, thelevels of resistin and adiponectin were unaffected by the intervention,while CRP levels increased within this short time period suggestingthat low-grade inflammation can occur early in the process ofdeveloping a metabolic syndrome.
|
|
